Watering Problem

Anonymous-0 · Jun 4, 2013

I've got a watering problem for ya'll.

I've got a 1.25" water line running 120' breaking into two 3/4" and running another 120' Then breaking into three 1/2" lines and another 10-20'.

Anyone know if what it will take to get 3GPM out of each of the 1/2" lines?

Dave in Tx · Jun 4, 2013

If you are taking 3gpm off each half inch line at the same time you will need a water supply of 10 gpm at probably 50 to 60 psi. My question would be why not run 1.25 line all the way/? Extra cost would have been little and water volume would have been increased greatly.

Geo-TH,In · Jun 4, 2013

Don't know your answer. I can tell you I have 150 ft of 3/4 black plastic running to the barn and 2 75 ft 3/4 inch garden hoses, making a total of 300 feet. Actually a little more, I need to factor the distance from the well to the house. Add another 50 ft of 1 inch. That said, I can get 12 gallons per minute out of one hose. Have a 1/2 hp pump and it shuts off at 50 psi.

So, do you have a total of 6 20 ft 1/2 lines?

If I put 6 1/2 hoses on two 3/4 inches hoses, I could only get about 2 gpm from each hose.

I'm going to guess, You will need a bigger pump and higher pressure.
George

Texasmark1 · Jun 4, 2013

3 gallons per minute is about what you get when you open the sink faucet with no reducer in the end.....not much.

I don't have the numbers in front of me on pipe material losses, diameter vs pressure drop, or diameter vs recommended flow, but I run my whole place, house, yard, shop, barn, watering trough and the whole shebang off about 100' of 3/4" line from the meter to the main distribution point. It is
Schedule 20 PVC so the ID is probably more like what you would get with 1" iron pipe. From the dist. point it is another 100' of the same pipe to the house. House has 2 baths and modern kitchen with dishwater, washing machine and all.

Static water pressure used to be around 50# (much higher now) and it worked fine for years.

Do what Dave said and you will be done with it, less hassle, common pipe and fittings, more than enough volume and be done with it. You will spend more nickel and dimeing it than the large pipe and fittings cost in the first place.

What I have learned over the years is you can never have too large of a water line (within reason of course).

Mark

ss55 · Jun 4, 2013

You want 3 GPM from each of six 1/2 inch outlets, for 18 GPM total?

The presssure drop will depend mostly on how the connections are laid out. Blind T-connectors and tight right angle turns can create more pressure lose than a long straight section of pipe. Elevation changes add 1/2 PSI of back pressure per extra foot of elevation.

Do you need to supply any pressure at the six outlets?

showcrop · Jun 5, 2013

Google "friction loss". According to the charts you should be good, though close to the edge. I remember from fire service that though fittings reduce flow by a certain amount that the loss is primarily a function of the distance.

mkirsch · Jun 5, 2013

So is it 3, or 6, 1/2" lines?

Watering Problem

Anonymous-0

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Dave in Tx

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Geo-TH,In

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Texasmark1

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ss55

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showcrop

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mkirsch

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